» Avoid going outside during dawn or dusk when mosquitoes are most active.

Despite the fact that mosquitoes have tested positive for West Nile virus, officials with Weld County and the city of Greeley say mosquito control programs are in full swing, and there is little reason for residents to worry.

One pool of mosquito traps set by the county in early July tested positive for West Nile virus, according to a news release issued Friday from the Weld County Department of Public Health and Environment.

This isn't unusual, or particularly alarming, said Eric Aakko, spokesman for the health department.

"A decade ago, the rate of infection was significantly higher," he said.

Aakko said that this is all due to the varying weather patterns in the state. When there's a wetter year on record, there's more mosquitoes in the air. That means more potential carriers of the virus. West Nile symptoms can take three to 14 days to manifest, and there is no vaccine or treatment to prevent infection.

"Our average rate is 20-30 cases a year," he said.

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Of those infected with West Nile Fever, only a small subset will go on to develop severe neurological effects, which can sometimes be fatal.

Weld County saw 27 human cases of the virus last year. This year there's only been one case in the entire state of Colorado. Aakko said that's because residents are doing their part to combat West Nile.

"The public is listening, and that's why the numbers have plateaued," he said.

Still, the hot months of July and August are ideal for mosquitoes and for West Nile virus. Aakko encouraged residents to take precautions against mosquitoes. They are most active at dawn and dusk, and congregate near standing bodies of water. Insect repellent and adequate clothing should be used when near these areas.

"Mosquito season is just getting started," he said.

Greeley and Weld County both have mosquito-control programs. Weld County sets traps on a weekly basis, but it leaves the actual act of pest control to municipalities. For several years, the city of Greeley has contracted its mosquito control out to Vector Disease Control International, which works to combat mosquitoes in Greeley.

"There's technicians out there every day," said Doc Weissmann, an entomologist with Vector Disease Control.

Most modern pest management systems focus on monitoring traps and other water sources, and then killing larvae through waterborne bacteria. Any source of standing water is a potential breeding ground for mosquitoes, and sometimes just monitoring water isn't enough.

When the larvae mature into adults, they bring out spray trucks. According to Joel Hemesath, director of public works for Greeley, officials spray about once a week based on the trap numbers.

"We'll probably be spraying until the end of the year," he said.

Hemesath said Greeley's mosquito-control program is focused on city-owned property, such as parks and open spaces. He said when crews detect a large amount of mosquitoes on private property, city officials contact the property owners to let them know about the threat, but its up to the property owners to take appropriate action to address the problem.

Larry Lerwick, a landlord who owns property on the northeast corner of 65th Avenue and Chardonnay Street in southwest Greeley, said he's worried about the abundance mosquitoes in the area because of a drainage ditch in the neighborhood, and he'd like more to be done in that area.

"I've got renters that might not even move in there," he said. "We have rental houses and property to protect," he said.